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SPOKANE, Wash. - Three wildfires burning in grasslands south of Wenatchee, Washington, had grown to approximately 36.7 square miles, but had not destroyed any structures.

Firefighters on Wednesday were trying to prevent the fires from growing to protect property and sage grouse habitat.

The lightning-caused Spartan Fire burning nine miles southeast of Wenatchee grew to 11.7 square miles overnight and was 30 percent contained by 160 firefighters. The fire threatened about 80 structures.

The Sutherland Fire, burning 15 miles south of East Wenatchee, grew to 15.6 square miles and was 10 percent contained by 150 firefighters. About 30 structures were threatened.

The Straight Hollow Fire, 20 miles south of East Wenatchee, burned 9.3 square miles (24 square kilometers) and was 20 percent contained by 50 firefighters.

Related: How to build a wildfire defensible space around your home

Check the smoke and air quality here.

Photos: Lightning strikes spark Eastern Washington fires